Expansible hone



Patented Feb. 23, 1943 EXPANSIBLE HON E David A. Wallace, Detroit, Mich., assignor to Chrysler Corporation, Highland Park, Mich, a corporation of Delaware Application August 26, 1914), Serial No. 354,129

1 Claim. (Cl. 51- -184.1)

My present invention relates to expansible homes for finishing the surfaces of cylindrical bores. It is the principal object of the present invention to provide an improved expansible hone, the parts of which are relatively simple stitution and interchangeability of parts conyenient so that the structure may be quickly changed from one type of operating characteristics to another.

The present invention comprises a rigid, substantially cylindrical cage member formed of end pieces connected by integral vertical bars which form a substantially cylindrical cage. The adjacent surfaces of adjacent bars are so formed as to be substantially parallel to radii of the cylindrical member so as to form guiding surfaces for guiding movable tool holding members radially with respect to the cylindrical member. Radial movement of the tool holding members is accomplished by pneumatic -or hydraulic pressure applied to the interior of a fluid-impervious bag suspended between the end pieces and inside of the vertical bars, so that substantially equal pressure is applied simultaneously throughout the length of the plurality of tool holding bars when desired. The simplicity of manufacture and assembly of the present invention make it of greater utility than heretofore known expansible hones.

The present invention -is an improvement upon the invention expressed in my copending application, Serial No. 265,109, filed March 31, 1939.

The objects and advantages of the present invention should be-more readily apparent from the description of the accompanying specification and drawing wherein like numerals refer to like parts throughout.

In the drawing, Fig. 1 is a sectional view in elevation of an expansible hone constructed according to my present invention, the section being taken substantially along line Il of Fig. 2; and

Fig. 2 is a cross-section taken through the expansible hone' substantially along line 22 of Fig. 1.

The assembly, comprises a shank I!) having a crossbar H therethrough by means of which the shank may be engaged in a suitable chuck. The shank i is integral with a cup-shaped portion l2 of substantially increased diameter extending downward from its lower end, the lower portion of the flange thereof being smooth to provide a centering surface for engaging internal threads with the external threads at the upper end of a cage member l3 forming a part of the tool, which cage member is provided with an external flange M designed to engage the lower lip of the cup-shaped portion i2 and form and readily removable so as to make the suba rigid, fluid-tight seal. The shoulder fanned by the cup-shaped portion I2 is engaged bypn annular collar l5 fastened to the shank l.l by" convenient means such as set screws l5. Mount ed uponthe collar I5 is a fluid inlet collar 43 which is retained in position by an upper collar i8 flxedto the shank H] by convenient means such as set screws IS. -The inlet collar I1 is: provided with a threaded mouth to which,

may be affixed. a pipe (not shown) for admitting fluid thereinto and which communicates with a plurality of openings 2| extending radially inward through the shank l0 through the medium of a perforated intermediate ring 22 held between the packings 23 of a packing gland mounted inside of the inlet collar l1. Theconstrudtion provides a running gland wherebyfiuid may be forced into the interior of the shank ID or withdrawn therefrom while the tool is rotating. Bores 2i communicate with a' vertical bore 25 extending downward into a recess 26 in the top of the cup extension l2 of the shank 10 in which is located the upper end of a threaded tube 21 having its lower end vulcanized to a nipple 28 through which a central bore communicates with the interior of a fluid-impervious bag 30 suspended therefrom and lying within the central bore of the cage member II. The upper end of the bag 30 is rounded and fits into the rounded surface of an end piece 3i threaded to engage with internal threads on the cage i3, the lowerportion of the outer surface of the end piece 3| being of considerable length andengaging a similar smooth surface on the cage member I3 whereby to prevent the escape of fluid therebetween, just as fluid is prevented from escaping between the surfaces of the members l2 and I3. Between the upper surface of end piece 3i and the bottom of the cupshaped extension ii there is mounted a spacer 32 surrounding the nipple 28 and against which may be tightened a nut 33 engaging the threads of the tube 27 whereby the upper end of .the bag 30 may be conveniently heldin position with the opening thereinto in communication with the bore 25 in shank it The lower end of the bag at is also roundedand s held in position by a lower end piece'35 threaded into the lower end of the central bore of the cage member 03 and having an inner dished surface to match the rounded end of the bag 30,

The bag 30 is' formed of a resilient fluidimpervious material, such as rubber, or a polymerized chloroprene which may be of advan-'- tage in certain installations where oil is likely to attack rubber, and preferably has sufllcient rigidity to remain in contact with the walls of the central bore of the cage member II as illustrated in Figs. 1 and 2. 'In this position a slight amount of fluid pressure will begin to exert pressure against the inner surfaces of the vertical bars forming the cage member. Movable tool holder bars 4| are placed between the fixed bars ",the two sets of bars being of substantial radial thickness so thatthe meeting surfaces of through the cylindrical member, and the sides of. the slots so formed are substantially parallel to. radii of the cylindrical member so that substantially rectangular bars ll may be guided therein for radial sliding movement. The result cf so.shaping the cylindrical member is to form. thefixed bars" as substantially triangular members. Preferably the inwardly pointingwapices of the fixed bars 40 are truncated and the'corners thereof rounded outwardly so as not to have sharp corners likely to wear or cut the surface of the bag 30. Also, the inner surfaces of the rectangular bars II are preferably reentrantlyrounded' so as to fit the circumference of the bag 30 and provide better engagement therebetween, and likewise the inner edges of the bars 4| are preferably rounded so as to eliminate cuttingor abrading edges;

The longitudinally extending 'flxed bars 40 form 'acage between which the longitudinally extending movable bars I I are retained in retracted position by suitable means such as garter springs 42; and mounted at top andbottom, respectively, ofthe'cage member and engaging the ends of the movable bars so as to hold them in retracted position between the fixed bars. Admission of fluid under pressure such as air, inert gases, or any suitable liquid such as oil or water. causes'th'e vertical wall of'the bag 30 to expand simultaneously and equally in all directions wherever'permitted by the nature of the tool, thus causing the movable bars to slide radially outward equally and simultaneously throughout their length.- Any stretching of the material of the bag necessary to accommodate such outward bulging of the walls thereof is permitted due to the fact that the bag is attached at its upper end cated endlextending inward, substantiallyreconly and the lower end may shift in its seat in end -piece35'.- The fluid pressure overcomes the retractive forces of the springs 42 and I3 and permits the movable bars II to move outward.

When the fluid pressure is released, or if suction applied to the interiorr-of the bag 30, the

springs ,42 and 43 will retract the movable bars thus decreasing the effective diameter of the tool sothat it;may be inserted within a cylindrical,

, effective diameter of thevertical strips is preferably slightlyless than that of the cylindrical bore which is beingoperated upon, and the lower ends of the strips 46 are preferably bevelled to an effective diameter lesser than the largest diameter of thesurface" so as to permit ready inser-- tion ofthe tool into the bore.

Each of the movable bars ll is providedwith an abrading tools ill which are mounted upon metal strips 5! suitably fastened to the bars H. and the ends of which are preferably bent outward as at 52 so asto provide hooks for engaging the garter springs 42 and 43. When the movable bars are retracted the abrading tools are preferably extended to a lesser extent than the surfaces of the leather strips 46 so that longitudinal marks,

the effective diameter of the tool becomes greater than the diameter of the leather guiding strips.

The abrading tools may be. formed of natural or artificial stone or similar substances used for surface finishing various types of work pieces, and

various grades of abrasive maybe quickly inter- I changed by disengaging the springs 42 and ll" from the hooks s2 and withdrawing the movable bars I I. 7

Having described a preferred embodiment of mypresent invention, it should be apparent to those skilled in the art that the same permits of -modiflcations in detail and. arrangement. All i such modifications as come within the scope of be a part An expansible hone comprising a substantially cylindrical, member having a relatively thick wall through which a plurality of longitudinally extending radial slots extend and a central, longitudinally extending bore,1-the sides of said slots being substantially parallel to radii of said 'mem'- ber whereby the cross-section of each of the fixed bars extending longitudinally between slots is substantially trunco-pyramidal with the trunfinishing tools carried. by said tool holder-bars. resilient means carried by said member and retaming said tool holder bars in said slots, a fluidexpansible bag-in said central bore and having'a fluid transmitting opening thereinto whereby fluid pressure may be exerted against the interior surface of said bag in orderto expand the same into said slots and force said tool holder bars radially outward against the restraint of said resilient means, and strips of cushioning material mounted on the outer surfaces of the fixed bars a between said slots at an effective diameter greater ---said rounded lower end.

than the eflective diameter of said surface flnlsh-' ing tools whensaid tool holder bars have been,

retracted by said resilient means and lesser than the effective diameter of'said surface finishing tools when said tool holder bars have been forced outward by said fluid-,expansible bag, said cylindrical member having a rounded lower end by means of which they hone may be guided into a bore to be finished, and said strips havingtheir lower extremitiesa'djacent to, and at an effective diameter lesser than the greatest diameter of,

DAVID A. WALLACE. 

